1. Field of the Invention
The present invention relates to a hue max min diff (HMMD) color model, and more particularly for quantizing colors using the HMMD space and color spreading. The present invention relates a content based image searching by building a color histogram.
2. Discussion of Related Art
Currently, extensive research for searching an image based upon the contents is actively being conducted. In response, commercial image searching apparatus and/or applications program are being developed to meet the demand for an improved content based image searching. For example, using contents such as a color temperature change, an external cross magnetic field, and a color homogeneity have been proposed for searching a human image. For color homogeneity, a color space must first be quantized or expressed as numerical values.
The most important information for use in the content based image searching is the color information. Accordingly, an effective performance of an image searching apparatus or applications program depends greatly on an accurate method for extracting the color information.
Generally, the number of different colors which can theoretically be expressed by a computer has been steadily increasing. However, the number of colors which can be displayed by the computer is limited by the available number of quantized colors. A problem arises because the number of quantized colors is less than the number of the colors which can be expressed. Quantization is a procedure of color mapping from M number of colors to N number of colors when M greater than  greater than N, where M and N are positive integral numbers.
In computers, a color is expressed utilizing the RGB color model based upon the three primary colors of red R, green G, and blue B. However, the RGB space is hardware oriented and a limitation exists in expressing the color changes such that the change can be sensed by the human eye. Thus, the RGB space is often converted into a user oriented HSV color model based upon a hue H, saturation S and value V, then converted back to the RGB space by quantization.
Content based image searching apparatuses or applications programs utilizing the HSV space have been proposed by Foley and Dam in xe2x80x9cFundamental of Interactive Computer Graphicsxe2x80x9d, Addison Wesley, pp. 613-16, 1984; Smith in xe2x80x9cIntegrated Spatial and Feature Image Systems: Retrieval, Analysis and Compressionxe2x80x9d, Ph.D. thesis, Columbia University 1997; Virage searching engine, web cite: www.virago.com; and U.S. Pat. No. 5,751,286.
However, even within the HSV space, a range of color changes which can be sensed by the human eye are differently displayed. Also, a simple quantization of the colors in the HSV space does not result in a uniform expression of colors. On the other hand, to quantize the saturation vector value in consideration of the color change sensed by the human eye, the selection of a quantization model would be difficult and many complicated calculations are required. Thus, the performance of the content based image searching system using the HSV space deteriorates.
Accordingly, a color space and a color quantization method utilizing a color space capable of performing color quantization in consideration of the color changes sensed by the human eye and capable of uniformly dividing the colors are required.
Accordingly, an object of the present invention is to solve at least the problems and disadvantages of the related art.
An object of the present invention is to provide a new color model HMMD based upon the hue, the shade (max), the tint (min), the tone (diff), and the brightness (sum).
Another object of the present invention is to provide a method for quantizing a color using the HMMD space and color spreading.
A further object of the present invention is to provide a method for quantizing a color in consideration of the color changes sensed by the human eye.
Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objects and advantages of the invention may be realized and attained as particularly pointed out in the appended claims.
To achieve the objects and in accordance with the purposes of the invention, as embodied and broadly described herein, the HMMD color space according to the present invention includes the hue, max, min, diff and sum. The method for quantizing a color using the HMMD color space and color spreading according to the present invention determines a distance between a color to be mapped and the neighboring colors and maps the color utilizing the determined distance as weights.